Insulator



R; STEWART Sept. 3, 1940.

INSULATOR Filed Nov. 14, 1939 2 Sheets-Sheet l l l'llllll Sept. 3, 1940. R. STEWART 2,213,922

INSULATOR Filed Nov. 14. 1939 2 Sheets-Sheet 2 ffy 5. 1f

Patented Sept.. 3, 1940 STATES PATET Fl INSULATR Rcbert Stewart,

tinental-Diamond Ri Newark, libel.: assigner to Conbre Company, Newark,

3 Claims.

This invention relates to insulators and, more particularly, to an insulator incorporating articial resins, and has for an important object Ythereof the provision of a device of this character 5 having a very high electrical resistance.

Another object of the invention is the provision of a structure of this character which may be readily and cheaply produced, 'which will be durable and eincient in service and a general iml@ provement in the art.

' These"--a ,d other objects I attain by the con struction "own in the accompanying drawings wherein, for the' 'purpose of illustration, I have shown a preferred embodiment of my invention l5 and wherein:

Fig. 1 isga perspective view of an insulator constructed in accordance with my invention;

Fig. 2 is avertical sectional view therethrough;

Fig. 3 is a perspective view partially broken away, showing the as emblage partially completed; and

Fig. 4 is a combined perspective of the sections of the core employed, portions thereof being broken away to show the interior construction.

25 In accordance with my invention, I employ a multipiece core, shown more particularly in Fig. 4. This core comprises end sections l and an intermediate section H. Each of these sections is formed of a plurality of plies of resin-impregnated 30 fabric, the plies of the end 'sections being arranged in the direction of the axis of the section and those of the intermediate section -ll being arranged transversely to the axis. These sections are either ,partially or completely cured, as de- 35 sired, and the exterior surfaces thereof are corrugated as, for example, bycoarsely threading the same, although it .will be obvious that preformed corrugations may be provided during the curing or partial curing of the sections. This 4o core is then Wrapped With resin-impregnated material indicated at I2, following which it is molded. During the molding operation, the heat and pressure utilized will serve to bind the outer covering to the core as well as to form the same and will, d furthermore, serve, if the core is but partially cured, to complete the curing thereof. The inner layers of the covering will be forced into the corrugations, providing a secure interlock between the outer covering and core, as more clearly shown 50 in Fig. 2 of the drawings. The end sections are then bored and threaded, as at I3, for reception of the usual yattaching screws.

I have foundthat a construction of this character provides much higher electrical resistance than is available in the usual construction Wherein all of the laminations of the insulator extend longitudinally of the insulator. For example, two insulators of the same size and general specications, but one incorporating the transverse laminations in the core as hereinbefore described, and 5 Kthe other formed in the usual manner, showed an increase in resistance in favor of the type herein illustrated of more than 300 per cent. This is, undoubtedly, due to the fact that the dielectric resistance of the material is less in l0 the direction of lamination than in a direction transverse thereto, and to the fact that the barrier formed by the intermediate section i l is disposed in the direct path of highest dielectric stress. It is possible, but not practical, to place al1 of the laminations of the core transversely of the axis thereof due to the fact that strain insulators oi the type illustrated must oiTer considerable resistance to pull in the zone of the connections made thereto. Such resistance is best oiered by the axial arrangement of the lamina- .tions and for this reason it is advisable that the core be made sectional, as illustrated.

Threading of the core, or otherwise corrugatng the same, insures a good mechanical connection, even though the core be completely converted prior to the final molding, and this corrugation is of further value in that it increases the path through which current must pass in moving about the intermediate section.

Since the construction illustrated is capable of considerable modification without in any way departing from thevspirit of the invention, I do not wish to be understood as limiting myself thereto except as hereinafter claimed.

I claim:

1. An insulator composed entirely of articialresin-impregnated laminated material and having sockets in its ends, said insulator comprising a core coextensive with the body of the insulator and of greater diameter than said sockets and in l the ends of which the sockets are axially formed,

.and an outer covering, said core and covering being axially interlocked and the core comprising end sections having said sockets and an intermediate section in which the material is in plies transverse to the insulator axis, the end sections of the core and said covering consisting of plies of the material paralleling said axis.

' 2. An insulator composed entirely of articial- 50 resin-impregnated laminated material and having sockets in its ends. said insulator comprising a. core coextensive with the body of the insulator and of greater diameter than said'sockets and in the ends of which the sockets are axially formed,

4 5 core and said covering consisting of plies of the material paralleling said axis.

3. An insulator composed entirely of articialresin-impregnated material, said insulator comprising a preformed core coextensive with the in o sulator body and consisting of end sections and an intermediate section, the intermediate -section comprising plies of fabric disposed transversely to the axis of the core, the end sections comprising plies of fabric disposed parallel to the axis of the core, the exterior of the core being circumferentially corrugated, and a covering molded upon said core, said end sections having axial sockets formed therein for the reception of t attaching elements, said sockets being of less diameter and length than said end sections.

ROBERT STEWART. 

